In recent years, a variable resistive element has gained attention as a succession candidate for a floating-gate type semiconductor memory. A variable resistive memory can store data in non-volatile by changing a resistance of a variable resistive layer based on impression of a voltage pulse. The variable resistive memory has a simple structure such as a two-terminal structure. Therefore, by applying the variable resistive memory to a cross-point type memory cell array, it is easily possible to construct a large-capacity memory as compared to a case where the floating-gate type semiconductor memory is applied to a cross-point type memory cell array.
In the case of the cross-point type, in order to suppress possible influence of a bypass current, it is essential that a reverse current of the memory cell is sufficiently smaller than a forward current. Therefore, normally, the memory cell is structured as serial connections of variable resistive elements and diodes. However, in such case, due to a difference between the variable resistive element and the diode, and to a thickness of the diode in a current pass direction, manufacturing processes tend to become complicated requiring high-cost while an operating voltage increases.
On the other hand, technologies for realizing a variable resistive element having a rectifying property therein have been developing by applying a stack structure of a rectifier function layer and a retention layer to the memory cell, a retention characteristic of the rectifier functional layer at an on-state (low resistance state) being poor while a retention characteristic of the retention layer at a on-state being good. However, even in such case, the operating voltage still increases as compared to the memory cell constructed only from the retention layer.